Date of Award

7-2008

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Dr. Christopher Norment

Abstract

Over the course of the last century, shrubland habitat in the northeastern United States has declined due to farmland abandonment, deforestation, reforestation, human population growth and increased anthropogenic efforts to limit natural disturbances. In turn, these landscape alterations have caused a decline in the shrubland guild of birds in the northeastern United States, specifically the Great Lakes Plain Region. Declines have been so significant that wildlife managers must actively conserve existing shrublands and create new habitat to support shrubland birds. Thus, to offer suggestions for conservation and management of shrubland habitats and the birds that rely on them, I studied shrubland birds and their associated habitats in the Great Lakes Plains Region over two breeding periods in 2006 and 2007. My results revealed few consistent patterns in the bird habitat models developed from my data. This was not surprising, as most areas studied drastically varied in both vegetation community structure and composition. In addition, shrubland birds are often characterized by broad habitat preferences. Thus, the majority of the results can best be examined on a site-specific and species-specific basis. Some habitat variables did stand out in the models. Shrub hit diversity seemed to be an important predictor of shrubland bird abundance. Shrubland area also came up as a significant variable in a number of bird-habitat models. Even with the lack of consistency among my models, my data, along with other research, yielded management recommendations that should increase shrubland habitat, which should benefit shrubland birds. There are four main characteristics of shrubland habitat that need to be considered in order to increase and sustain declining species of shrubland birds: (1) shrublands should be relatively large (>0.6 ha) in area, regardless of area-sensitivity (or lack-there-of) of shrubland birds; (2) shrublands should be adjacent or near other shrubland sites in order to avoid displacement of shrubland and forest birds; (3) shrublands need to be reasonably accessible to brush hogs and tractors so that they can be maintained without issue; and (4) shrublands should be created and/or maintained from existing shrublands, grasslands, or old fields, as shrublands converted from forest habitats are often of poor quality. When looking at the "big picture" of shrub land management, there is no one management practice that is best. Thus, management should be adaptive so that practices can be changed when new data becomes available, without compromising explicit management and conservation goals.

Share

COinS